Investigations on the Evolution of Akron Abrasion Process of SBR Vulcanizates

The Akron abrasion processes of two different kinds of SBR (1502 and T2000R) were studies in detail in this paper. The whole Akron abrasion process (1.61 km) was divided equally into six stages, and the abrasion loss at every stage was measured. The crosslink density and abrasion pattern of every abrasion stage were investigated respectively by Nuclear Magnetic Resonance Crosslink-density Spectrometry (NMR-CDS) and optical microscopy. The effects of hot-air aging and carbon black fraction on the abrasion processes and abrasion resistance are also discussed. For both unfilled SBR1502 and SBRT2000R, it was found that the trend in the plot of abrasion loss against stage number was similar to each other. Their abrasion loss at different stages was different, and it had a maximum value at the third stage. The crosslink density decreased as the number of revolutions increased, while it increased sharply at 6000 revolutions due to the abraded surface being torn off. The microscopic studies showed that the abrasion began at 100 revolutions, and the coarse Schallamach abrasion pattern formed at 1000 revolutions. The ridges here were more or less across the circumference of the specimen. For filled vulcanizates, the abrasion resistance improved as the fraction of carbon black increased. The trend in abrasion loss plot was similar to that of the unfilled samples when the content of carbon black was lower than 30 phr. However, only a slight variation was observed in the abrasion loss at different stages when the content of carbon black was greater than 30 phr.